1. Field of the Invention
The present invention relates to a turbomachine with coatings on the rotor and stator sections thereof.
2. Discussion of Background Information
In turbomachines such as gas turbines and steam turbines, it is necessary for radial gaps between rotating and static machine parts to be sealed off in order to prevent secondary flow losses. This applies for example to the sealing of the radial gap between a guide blade tip and an opposite disk vane or between a rotor blade tip and an opposite stator section.
To seal off the radial gaps, use is conventionally made of labyrinth seals. It has however been found that the machine parts that form the labyrinth seals are subject to high levels of wear and intense heating in the event of rubbing. The rubbing and the heating can lead to cracks, which can have severe consequences in particular for the rotating parts. The rotating part is thus normally provided with so-called armoring. The armoring is in particular a hard layer applied by means of a thermal spraying process. By contrast, the static part remains uncoated and is thus soft in relation to the rotating component. As a result, the static component becomes correspondingly abraded and worn in the event of rubbing. The armorings are however normally rough, which leads to corresponding heating in the event of rubbing. Furthermore, it has been found that the armorings have a tendency to spall.
It is an object of the invention to create a turbomachine which permits durable sealing and/or a reduction of a radial gap between a rotor and a stator of the turbomachine.